---
id: CVE-2026-22980
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  nfsd: provide locking for v4_end_grace

  Writing to v4_end_grace can race with server shutdown and result in
  memory being accessed after it was freed - reclaim_str_hasht…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  nfsd: provide locking for v4_end_grace

  Writing to v4_end_grace can race with server shutdown and result in
  memory being accessed after it was freed - reclaim_str_hasht…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-416
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 3.18, < 5.10.248'
  - 'linux_kernel >= 5.11, < 5.15.198'
  - 'linux_kernel >= 5.16, < 6.1.161'
  - 'linux_kernel >= 6.2, < 6.6.121'
  - 'linux_kernel >= 6.7, < 6.12.66'
  - 'linux_kernel >= 6.13, < 6.18.6'
  - linux_kernel = 6.19
patched:
  - linux_kernel 6.18.6
published: '2026-01-23'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T02:18:38.463'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-22980'
references:
  - url: 'https://git.kernel.org/stable/c/06600719d0f7a723811c45e4d51f5b742f345309'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2857bd59feb63fcf40fe4baf55401baea6b4feb4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/34eb22836e0cdba093baac66599d68c4cd245a9d'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/53f07d095e7e680c5e4569a55a019f2c0348cdc6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ba4811c8b433bfa681729ca42cc62b6034f223b0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ca97360860eb02e3ae4ba42c19b439a0fcecbf06'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e8bfa2401d4c51eca6e48e9b33c798828ca9df61'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-019113.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-457936.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00147
epssPercentile: 0.0391
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-06-16T20:36:55.336499Z'
ingestedAt: '2026-09-08T15:33:26.994Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

nfsd: provide locking for v4_end_grace

Writing to v4_end_grace can race with server shutdown and result in
memory being accessed after it was freed - reclaim_str_hashtbl in
particularly.

We cannot hold nfsd_mutex across the nfsd4_end_grace() call as that is
held while client_tracking_op->init() is called and that can wait for
an upcall to nfsdcltrack which can write to v4_end_grace, resulting in a
deadlock.

nfsd4_end_grace() is also called by the landromat work queue and this
doesn't require locking as server shutdown will stop the work and wait
for it before freeing anything that nfsd4_end_grace() might access.

However, we must be sure that writing to v4_end_grace doesn't restart
the work item after shutdown has already waited for it.  For this we
add a new flag protected with nn->client_lock.  It is set only while it
is safe to make client tracking calls, and v4_end_grace only schedules
work while the flag is set with the spinlock held.

So this patch adds a nfsd_net field "client_tracking_active" which is
set as described.  Another field "grace_end_forced", is set when
v4_end_grace is written.  After this is set, and providing
client_tracking_active is set, the laundromat is scheduled.
This "grace_end_forced" field bypasses other checks for whether the
grace period has finished.

This resolves a race which can result in use-after-free.

## Affected

- `linux_kernel >= 3.18, < 5.10.248`
- `linux_kernel >= 5.11, < 5.15.198`
- `linux_kernel >= 5.16, < 6.1.161`
- `linux_kernel >= 6.2, < 6.6.121`
- `linux_kernel >= 6.7, < 6.12.66`
- `linux_kernel >= 6.13, < 6.18.6`
- `linux_kernel = 6.19`

## Remediation

Upgrade past the affected range:

- `linux_kernel 6.18.6`